The broad objective of the proposed research is to establish the mechanism for cytochrome c in respiration linked electron transport. The specific goals are: (1) To answer the question of whether protein-protein interaction in the transport chain is resolved in time from electron transfer. This will done by a rapid mixing kinetic analysis with dual monitoring of protein binding and electron transfer. (2) To explain the inhibitory effect of polylysine on cytochrome systems. This will be approached by studying the interaction of polylysine with a bacterial cytochrome, both native and chemically modified. This bacterial cytochrome is completely homologous to eukaryotic cytochrome and possesses unique structural features which will aid in the study. (3) To determine the active site of cytochrome. A chemical modification of the exposed heme in cytochrome will be used to probe reactivity at this presumed active site for electron transfer.